KX3 - KXPD3 Socket, Plug, and Schematic Questions

[Richard-2]

Hello,
   Why is source 3V3D connected to Pin 3 of the KXPD3?
   I have made (but not yet used) an interface cable to connect external
paddles to the KXPD3 jack.  The  KXPD3 Schematic shows Pin 3 of the plug
grounded inside the KXPD3.  However, Page 2 of 8 of the Control Panel
schematics shows 3.3 Volts (3V3D) connected to pin 3 of the KX3 socket
through R110.
   Testing by another ham found that connecting Pin 1 (grounded inside
KX3) to his external key common and the Dit and Dah leads to pins 2 and
4 worked fb.  The KXPD3 schematic shows Pin 1 not used.
   My KX3 socket pin measurements to chassis:  Pin 1: Grounded,  Pin 2:  
11k,  Pin 3:  2.1k,  Pin 4: 11k
   Is Pin 1 or Pin 3 the common contact terminal inside the KXPD3? Is
Pin 3 grounded inside the KXPD3?  (I would ring it out, but I don't own
one.)
   Do nDASHALT and nDOTALT go low (like the side key jack) or high to
indicate contact closure?
   If the former, why is 3V3D connected to the KXPD3?
   Thanks for any assistance to help me understand.
    73, Richard, AI4SH


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[Lyle Johnson]

It is for unspecified possible future use.

73,

Lyle KK7P

> ...Why is source 3V3D connected to Pin 3 of the KXPD3?
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[Lou Voerman W2ROW]

There was a discussion of this topic on the KX3 group. The dot and dash paddles (pins 3 and 4) need to make contact with ground (pin 1). The original version of the KXPD3 had a design flaw on the circuit board which followed the diagram in the published KXPD3 schematic dated March 2012. This version of the KXPD3 got its ground through the screws connecting the KXPD3 to the KX3 chassis.

The KXPD3 upgrade fixed this problem with a circuit board replacement and the new version of the KXPD3 now gets its ground connection from pin 1 and the chassis, pin 3 is not connected.

During the discussion Wayne said that the original intent of pin 3 was to provide memory button functions (different resistances to ground for each memory button) but this was not implemented.

This is my understanding of the situation. I have no insider knowledge. I do believe that the KXPD3 schematic needs updating to reflect the new version.

Lou W2ROW

Richard-2 wrote

Hello,
   Why is source 3V3D connected to Pin 3 of the KXPD3?
   I have made (but not yet used) an interface cable to connect external
paddles to the KXPD3 jack.  The  KXPD3 Schematic shows Pin 3 of the plug
grounded inside the KXPD3.  However, Page 2 of 8 of the Control Panel
schematics shows 3.3 Volts (3V3D) connected to pin 3 of the KX3 socket
through R110.
   Testing by another ham found that connecting Pin 1 (grounded inside
KX3) to his external key common and the Dit and Dah leads to pins 2 and
4 worked fb.  The KXPD3 schematic shows Pin 1 not used.
   My KX3 socket pin measurements to chassis:  Pin 1: Grounded,  Pin 2:  
11k,  Pin 3:  2.1k,  Pin 4: 11k
   Is Pin 1 or Pin 3 the common contact terminal inside the KXPD3? Is
Pin 3 grounded inside the KXPD3?  (I would ring it out, but I don't own
one.)
   Do nDASHALT and nDOTALT go low (like the side key jack) or high to
indicate contact closure?
   If the former, why is 3V3D connected to the KXPD3?
   Thanks for any assistance to help me understand.
    73, Richard, AI4SH


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[Richard-2]

Hello Lou,
   Thanks for the helpful information!
      Richard, AI4SH
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